Rapid Diagnostic Test vs Real-Time PCR (qPCR)
There are several diagnostic tests that have been authorized for Emergency Use by the FDA for diagnosis of a wide range of infections. Notably, these diagnostic tests aim at identifying an infected individual from a non-infected person, using different working principles and duration for the tests vary. Diagnostic tests can be molecular-based or immuno-assays.
The most common tests are:
Rapid Diagnostic tests
- They are mainly serological tests principally working to detect immune reactive elements i.e antibodies or detecting the pathogenic antigens.
- They are mainly used for screening of diseases, and at a health care worker’s convinces hence, the are point-of-care diagnostic tests
Real-Time PCR (qPCR)
- This is a molecular-based technique that principally works to qualitatively detect the presence of pathogen genome i.e RNA or DNA.
- The genome undergoes different stages of processing before identification followed by sequencing for classification of the pathogen strains.
Differences between the Rapid Diagnostic Test and Real-Time PCR (qPCR)
Rapid Diagnostic Test
Real-Time PCR (qPCR)
|Sample||They require whole blood or plasma or serum samples for tests or biopsy.||The test uses liquid or solid samples depending on the condition of the test e.g Respiratory infection requires nasal swabs or nasopharyngeal swabs.|
|Principle||Qualitative and semi-qualitative in-vitro devices.||Qualitative and quantitative in-vitro medical devices.|
|Types||Rapid Antibody test
Rapid Antigen test
|quantitative real-time PCR
semi-quantitative real-time PCR
|Objectivity||The test aims at identifying and/or detecting antibodies, majorly IgG and/or IgM.
Detection of antigens (pathogen particles ) in blood.
|The test aims at amplifying and detecting the pathogen genome (RNA and DNA).|
|Duration of Test||It takes approximately 15 minutes to 2 hours to get the test result.||It can take 1 hour to 48 hours to get the test result.|
|Reagents||The test uses a solution buffer to allow the capillary tube.||Several PCR reagents are used.|
|Instrumentation||It is a simple chromatographic capillary tube.||It is complex with several compartments each performing a series of protocols.|
|Procedure||Most are one-step procedures.||They involved a series of steps including denaturation, annealing, and extension.|
|Platforms||Lateral flow tests
|High-throughput platforms which include Dynamic Array Chip, TaqMan Open array, and SmartChip.|
|Sensitivity and specificity||Most have high sensitivity >95% and specificity of >99%.||The sensitivity of most tests ranges from >95% and specificity of >83%.|
|Applications||– Used for preliminary or emergency medical screening.
– Used in point-of-care testing for diagnosis.
– Used for diagnosis of a wide range of diseases including Malaria, HIV, TB, Influenza, Dengue fever, Strep B, Syphilis, COVID-19.
|– Research Applications
– Genetic cloning
– Genetic disease diagnosis
– Cancer detection
|Results||A positive test indicates the presence of Antibodies against the specific pathogen or presence of antigens of the pathogen.
A negative test indicates the absence of antibodies produced against the pathogen or absence of pathogenic antigens.
|Positive results indicate the detection of pathogen genome RNA/DNA and negative results indicate a lack of RNA/DNA genome.|
|Portability and Cost||They are small and easily portable and inexpensive.||Most are large machines difficult to move from one place to another and they are expensive to manufacture and purchase.|
|Examples||Rapid HIV Test
Rapid Plasma Reagin
Rapid Influenza Diagnostic Test
Malaria Antigen Detection Test
Rapid Strep B Test
Rapid Urease test
Rapid Dengue test
Syphilis Rapid Test
Tuberculosis IgM/IgG Rapid test
Influenza Real-Time PCR
Parasitic Real-Time PCR
Fungal Real-Time PCR
Bacterial Real-Time PCR
References and Sources